Stem cells from which connective tissue, bone, cartilage, and the circulatory and lymphatic systems develop. Mesenchymal stem cells are found in the mesenchyme, the part of the embryonic mesoderm that consists of loosely packed, fusiform or stellate unspecialized cells.

Cells found mainly in the bone marrow that give rise to a number of tissues, including bone, cartilage (the lining of joints), muscle, fat and connective tissue (tissue that is in between organs and structures in the body).